Cannabinoids have long been known to affect development as well as to affect several physiological functions such as pain, nausea, immunologic state, introcular pressure, bronchospasm, etc., in humans. Two specific cannabinoid receptors have been cloned so far: CB1, mostly present in neuronal structures, and CB2, found in cells of the immune system. Initially, we thoroughly studied the normal distribution of both receptor mRNAs (using in situ hybridization, Northern blotting, and PCR techniques) as well as the proteins (using specific antibodies to the receptors). Then, we designed a gene construct to produce a transgenic mouse that genetically lacks the CB2 receptor mRNA to study the consequences of such a deficiency. Presently, we are in the process of testing the immune functions of the CB2 knock-out transgenic mice. In addition, we are also attempting to breed a transgenic mouse that lacks both CB1 and CB2 receptors using a transgenic line that lacks the CB1 receptor (made by T. Bonner).